A typical heat sink assembling process using a phase change material as thermal transfer interface requires sending a whole assembly unit to an oven and heating up the whole assembly unit, such that the heat sink and/or other electronic components are able to be bonded to the computer chips and/or PCB (Printed Circuit Board). It is wasteful of energy to heat up the whole assembly unit. Further, thermo-expansion that results from heating the whole assembly can cause alignment and positioning problems of computer chips on the circuit board.